Methods, wireless communications networks and infrastructure equipment

ABSTRACT

A method of controlling communications within a wireless communications network is provided. The communications network comprises a plurality of infrastructure equipment each being configured to communicate with one or more others of the infrastructure equipment via a backhaul communications link, one or more of the infrastructure equipment each being configured to communicate with one or more communications devices via a wireless access interface. The method comprises receiving, at a first of the infrastructure equipment acting as a donor node connected to a core network part of the wireless communications network, from a second of the infrastructure equipment, information relating to each of a plurality of different communications paths from the second infrastructure equipment to the first infrastructure equipment via one or more others of the infrastructure equipment acting as relay nodes, determining, based on the received information relating to the plurality of different communications paths, that either at least a part of a new communications path exists between the first of the infrastructure equipment and the second of the infrastructure equipment or at least a part of a previously known communications path no longer exists between the first of the infrastructure equipment and the second of the infrastructure equipment, and updating a communications path list by either adding the at least the part of the new communications path or deleting the at least the part of the previously known communications path that no longer exists.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on PCT filing PCT/EP2019/056656, filedMar. 18, 2019, which claims priority to EP 18164770.2, filed Mar. 28,2018, the entire contents of each are incorporated herein by reference.

BACKGROUND Field of Disclosure

The present disclosure relates to methods and apparatus for themanagement of communications routes between various infrastructureequipment and the core network on a wireless backhaul communicationslink in a wireless communications system.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Recent generation mobile telecommunication systems, such as those basedon the 3GPP defined UMTS and Long Term Evolution (LTE) architectures,are able to support a wider range of services than simple voice andmessaging services offered by previous generations of mobiletelecommunication systems. For example, with the improved radiointerface and enhanced data rates provided by LTE systems, a user isable to enjoy high data rate applications such as mobile video streamingand mobile video conferencing that would previously only have beenavailable via a fixed line data connection. In addition to supportingthese kinds of more sophisticated services and devices, it is alsoproposed for newer generation mobile telecommunication systems tosupport less complex services and devices which make use of the reliableand wide ranging coverage of newer generation mobile telecommunicationsystems without necessarily needing to rely on the high data ratesavailable in such systems. The demand to deploy such networks istherefore strong and the coverage area of these networks, i.e.geographic locations where access to the networks is possible, may beexpected to increase ever more rapidly.

Future wireless communications networks will therefore be expected toroutinely and efficiently support communications with a wider range ofdevices associated with a wider range of data traffic profiles and typesthan current systems are optimised to support. For example it isexpected future wireless communications networks will be expected toefficiently support communications with devices including reducedcomplexity devices, machine type communication (MTC) devices, highresolution video displays, virtual reality headsets and so on. Some ofthese different types of devices may be deployed in very large numbers,for example low complexity devices for supporting the “The Internet ofThings”, and may typically be associated with the transmissions ofrelatively small amounts of data with relatively high latency tolerance.

In view of this there is expected to be a desire for future wirelesscommunications networks, for example those which may be referred to as5G or new radio (NR) system/new radio access technology (RAT) systems,as well as future iterations/releases of existing systems, toefficiently support connectivity for a wide range of devices associatedwith different applications and different characteristic data trafficprofiles.

As radio technologies continue to improve, for example with thedevelopment of 5G, the possibility arises for these technologies to beused not only by infrastructure equipment to provide service to wirelesscommunications devices in a cell, but also for interconnectinginfrastructure equipment to provide a wireless backhaul. In view of thisthere is a need for the effective management of routes betweeninfrastructure equipment (which may through their wireless backhaullinks act as relay nodes) and the core network, when such infrastructureequipment may be located remotely from the core network.

SUMMARY OF THE DISCLOSURE

The present disclosure can help address or mitigate at least some of theissues discussed above.

Embodiments of the present technique can provide a method of controllingcommunications within a wireless communications network. Thecommunications network comprises a plurality of infrastructure equipmenteach being configured to communicate with one or more others of theinfrastructure equipment via a backhaul communications link, one or moreof the infrastructure equipment each being configured to communicatewith one or more communications devices via a wireless access interface.The method comprises receiving, at a first of the infrastructureequipment acting as a donor node connected to a core network part of thewireless communications network, from a second of the infrastructureequipment, information relating to each of a plurality of differentcommunications paths from the second infrastructure equipment to thefirst infrastructure equipment via one or more others of theinfrastructure equipment acting as relay nodes, determining, based onthe received information relating to the plurality of differentcommunications paths, that either at least a part of a newcommunications path exists between the first of the infrastructureequipment and the second of the infrastructure equipment or at least apart of a previously known communications path no longer exists betweenthe first of the infrastructure equipment and the second of theinfrastructure equipment, and updating a communications path list byeither adding the at least the part of the new communications path ordeleting the at least the part of the previously known communicationspath that no longer exists.

Respective aspects and features of the present disclosure are defined inthe appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the present technology. The described embodiments,together with further advantages, will be best understood by referenceto the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 schematically represents some aspects of a LTE-type wirelesstelecommunication system which may be configured to operate inaccordance with certain embodiments of the present disclosure;

FIG. 2 schematically represents some aspects of a new radio accesstechnology (RAT) wireless communications system which may be configuredto operate in accordance with certain embodiments of the presentdisclosure;

FIG. 3 is a schematic block diagram of some components of the wirelesscommunications system shown in FIG. 2 in more detail in order toillustrate example embodiments of the present technique;

FIG. 4 schematically represents some aspects of a wirelesstelecommunication network which may be configured to operate inaccordance with certain embodiments of the present disclosure;

FIG. 5 is reproduced from [3], and provides a first example of an IABdeployment scenario;

FIG. 6 is reproduced from [5], and provides a second example of an IABdeployment scenario in which there are multiple candidate routes eachcomprising multiple hops from the end node to the donor node;

FIG. 7 shows a part schematic, part message flow diagram ofcommunications in a wireless communications network in accordance withembodiments of the present technique; and

FIG. 8 shows a flow diagram illustrating a process of communications ina communications system in accordance with embodiments of the presenttechnique.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Long Term Evolution (LTE) Wireless Communications System FIG. 1 providesa schematic diagram illustrating some basic functionality of a mobiletelecommunications network/system 6 operating generally in accordancewith LTE principles, but which may also support other radio accesstechnologies, and which may be adapted to implement embodiments of thedisclosure as described herein. Various elements of FIG. 1 and certainaspects of their respective modes of operation are well-known anddefined in the relevant standards administered by the 3GPP® body, andalso described in many books on the subject, for example, Holma H. andToskala A [1]. It will be appreciated that operational aspects of thetelecommunications networks discussed herein which are not specificallydescribed (for example in relation to specific communication protocolsand physical channels for communicating between different elements) maybe implemented in accordance with any known techniques, for exampleaccording to the relevant standards and known proposed modifications andadditions to the relevant standards.

The network 6 includes a plurality of base stations 1 connected to acore network 2. Each base station provides a coverage area 3 (i.e. acell) within which data can be communicated to and from communicationsdevices 4.

Although each base station 1 is shown in FIG. 1 as a single entity, theskilled person will appreciate that some of the functions of the basestation may be carried out by disparate, inter-connected elements, suchas antennas, remote radio heads, amplifiers, etc. Collectively, one ormore base stations may form a radio access network.

Data is transmitted from base stations 1 to communications devices 4within their respective coverage areas 3 via a radio downlink. Data istransmitted from communications devices 4 to the base stations 1 via aradio uplink. The core network 2 routes data to and from thecommunications devices 4 via the respective base stations 1 and providesfunctions such as authentication, mobility management, charging and soon. Terminal devices may also be referred to as mobile stations, userequipment (UE), user terminal, mobile radio, communications device, andso forth.

Services provided by the core network 2 may include connectivity to theinternet or to external telephony services. The core network 2 mayfurther track the location of the communications devices 4 so that itcan efficiently contact (i.e. page) the communications devices 4 fortransmitting downlink data towards the communications devices 4.

Base stations, which are an example of network infrastructure equipment,may also be referred to as transceiver stations, nodeBs, e-nodeBs, eNB,g-nodeBs, gNB and so forth. In this regard different terminology isoften associated with different generations of wirelesstelecommunications systems for elements providing broadly comparablefunctionality. However, certain embodiments of the disclosure may beequally implemented in different generations of wirelesstelecommunications systems, and for simplicity certain terminology maybe used regardless of the underlying network architecture. That is tosay, the use of a specific term in relation to certain exampleimplementations is not intended to indicate these implementations arelimited to a certain generation of network that may be most associatedwith that particular terminology.

New Radio Access Technology (5G) Wireless Communications System

An example configuration of a wireless communications network which usessome of the terminology proposed for NR and 5G is shown in FIG. 2. A3GPP Study Item (SI) on New Radio Access Technology (NR) has beendefined [2]. In FIG. 2 a plurality of transmission and reception points(TRPs) 10 are connected to distributed control units (DUs) 41, 42 by aconnection interface represented as a line 16. Each of the TRPs 10 isarranged to transmit and receive signals via a wireless access interfacewithin a radio frequency bandwidth available to the wirelesscommunications network. Thus within a range for performing radiocommunications via the wireless access interface, each of the TRPs 10,forms a cell of the wireless communications network as represented by aline 12. As such wireless communications devices 14 which are within aradio communications range provided by the cells 12 can transmit andreceive signals to and from the TRPs 10 via the wireless accessinterface. Each of the distributed units 41, 42 are connected to acentral unit (CU) 40 (which may be referred to as a controlling node)via an interface 46. The central unit 40 is then connected to the a corenetwork 20 which may contain all other functions required to transmitdata for communicating to and from the wireless communications devicesand the core network 20 may be connected to other networks 30.

The elements of the wireless access network shown in FIG. 2 may operatein a similar way to corresponding elements of an LTE network asdescribed with regard to the example of FIG. 1. It will be appreciatedthat operational aspects of the telecommunications network representedin FIG. 2, and of other networks discussed herein in accordance withembodiments of the disclosure, which are not specifically described (forexample in relation to specific communication protocols and physicalchannels for communicating between different elements) may beimplemented in accordance with any known techniques, for exampleaccording to currently used approaches for implementing such operationalaspects of wireless telecommunications systems, e.g. in accordance withthe relevant standards.

The TRPs 10 of FIG. 2 may in part have a corresponding functionality toa base station or eNodeB of an LTE network. Similarly the communicationsdevices 14 may have a functionality corresponding to the UE devices 4known for operation with an LTE network. It will be appreciatedtherefore that operational aspects of a new RAT network (for example inrelation to specific communication protocols and physical channels forcommunicating between different elements) may be different to thoseknown from LTE or other known mobile telecommunications standards.However, it will also be appreciated that each of the core networkcomponent, base stations and communications devices of a new RAT networkwill be functionally similar to, respectively, the core networkcomponent, base stations and communications devices of an LTE wirelesscommunications network.

In terms of broad top-level functionality, the core network 20 of thenew RAT telecommunications system represented in FIG. 2 may be broadlyconsidered to correspond with the core network 2 represented in FIG. 1,and the respective central units 40 and their associated distributedunits/TRPs 10 may be broadly considered to provide functionalitycorresponding to the base stations 1 of FIG. 1. The term networkinfrastructure equipment/access node may be used to encompass theseelements and more conventional base station type elements of wirelesstelecommunications systems. Depending on the application at hand theresponsibility for scheduling transmissions which are scheduled on theradio interface between the respective distributed units and thecommunications devices may lie with the controlling node/central unitand/or the distributed units/TRPs. A communications device 14 isrepresented in FIG. 2 within the coverage area of the firstcommunication cell 12. This communications device 14 may thus exchangesignalling with the first central unit 40 in the first communicationcell 212 via one of the distributed units 10 associated with the firstcommunication cell 12.

It will further be appreciated that FIG. 2 represents merely one exampleof a proposed architecture for a new RAT telecommunications system inwhich approaches in accordance with the principles described herein maybe adopted, and the functionality disclosed herein may also be appliedin respect of wireless telecommunications systems having differentarchitectures. Thus certain embodiments of the disclosure as discussedherein may be implemented in wireless telecommunication systems/networksaccording to various different architectures, such as the examplearchitectures shown in FIGS. 1 and 2. It will thus be appreciated thespecific wireless telecommunications architecture in any givenimplementation is not of primary significance to the principlesdescribed herein. In this regard, certain embodiments of the disclosuremay be described generally in the context of communications betweennetwork infrastructure equipment/access nodes and a communicationsdevice, wherein the specific nature of the network infrastructureequipment/access node and the communications device will depend on thenetwork infrastructure for the implementation at hand. For example, insome scenarios the network infrastructure equipment/access node maycomprise a base station, such as an LTE-type base station 1 as shown inFIG. 1 which is adapted to provide functionality in accordance with theprinciples described herein, and in other examples the networkinfrastructure equipment may comprise a control unit/controlling node 40and/or a TRP 10 of the kind shown in FIG. 2 which is adapted to providefunctionality in accordance with the principles described herein.

A more detailed diagram of some of the components of the network shownin FIG. 2 is provided by FIG. 3. In FIG. 3, a TRP 10 as shown in FIG. 2comprises, as a simplified representation, a wireless transmitter 30, awireless receiver 32 and a controller or controlling processor 34 whichmay operate to control the transmitter 30 and the wireless receiver 32to transmit and receive radio signals to one or more UEs 14 within acell 12 formed by the TRP 10. As shown in FIG. 3, an example UE 14 isshown to include a corresponding transmitter 49, a receiver 48 and acontroller 44 which is configured to control the transmitter 49 and thereceiver 48 to transmit signals representing uplink data to the wirelesscommunications network via the wireless access interface formed by theTRP 10 and to receive downlink data as signals transmitted by thetransmitter 30 and received by the receiver 48 in accordance with theconventional operation.

The transmitters 30, 49, the receivers 32, 48 may include radiofrequency filters and amplifiers as well as signal processing componentsand devices in order to transmit and receive radio signals in accordancefor example with the 5G standard. The controllers 34, 44 may be, forexample, a microprocessor, a CPU, or a dedicated chipset, etc.,configured to carry out instructions which are stored on a computerreadable medium, such as a non-volatile memory. The processing stepsdescribed herein may be carried out by, for example, a microprocessor inconjunction with a random access memory, operating according toinstructions stored on a computer readable medium.

As shown in FIG. 3, the TRP 10 also includes a network interface 50which connects to the DU 42 via a physical interface 16. The networkinterface 50 therefore provides a communication link for data andsignalling traffic from the TRP 10 via the DU 42 and the CU 40 to thecore network 20.

The interface 46 between the DU 42 and the CU 40 is known as the F1interface which can be a physical or a logical interface. The F1interface 46 between CU and DU may operate in accordance withspecifications 3GPP TS 38.470 and 3GPP TS 38.473, and may be formed froma fibre optic or other wired high bandwidth connection. In one examplethe connection 16 from the TRP 10 to the DU 42 is via fibre optic. Theconnection between a TRP 10 and the core network 20 can be generallyreferred to as a backhaul, which comprises the interface 16 from thenetwork interface 50 of the TRP10 to the DU 42 and the F1 interface 46from the DU 42 to the CU 40.

Example arrangements of the present technique can be formed from awireless communications network corresponding to that shown in FIG. 1 or2, as shown in FIG. 4. FIG. 4 provides an example in which cells of awireless communications network are formed from infrastructure equipmentwhich are provided with an Integrated Access and Backhaul (IAB)capability. The wireless communications network 100 comprises the corenetwork 20 and a first, a second, a third and a fourth communicationsdevice (respectively 101, 102, 103 and 104) which may broadly correspondto the communications devices 4, 14 described above.

The wireless communications network 100 comprises a radio accessnetwork, comprising a first infrastructure equipment 110, a secondinfrastructure equipment 111, a third infrastructure equipment 112, anda fourth infrastructure equipment 113. Each of the infrastructureequipment provides a coverage area (i.e. a cell, not shown in FIG. 4)within which data can be communicated to and from the communicationsdevices 101 to 104. For example, the fourth infrastructure equipment 113provides a cell in which the third and fourth communications devices 103and 104 may obtain service. Data is transmitted from the fourthinfrastructure equipment 113 to the fourth communications device 104within its respective coverage area (not shown) via a radio downlink.Data is transmitted from the fourth communications device 104 to thefourth infrastructure equipment 113 via a radio uplink.

The infrastructure equipment 110 to 113 in FIG. 4 may correspond broadlyto the TRPs 10 of FIG. 2 and FIG. 3.

The first infrastructure equipment 110 in FIG. 4 is connected to thecore network 20 by means of one or a sequence of physical connections.The first infrastructure equipment 110 may comprise the TRP 10 (havingthe physical connection 16 to the DU 42) in combination with the DU 42(having a physical connection to the CU 40 by means of the F1 interface46) and the CU 40 (being connected by means of a physical connection tothe core network 20).

However, there is no physical connection between any of the secondinfrastructure equipment 111, the third infrastructure equipment 112,and the fourth infrastructure equipment 113 and the core network 20. Assuch, it may be necessary (or, otherwise determined to be appropriate)for data received from a communications device (i.e. uplink data), ordata for transmission to a communications device (i.e. downlink data) tobe transmitted to or from the core network 20 via infrastructureequipment (such as the first infrastructure equipment 110) which has aphysical connection to the core network 20, even if the communicationsdevice is not currently served by the first infrastructure equipment 110but is, for example, in the case of the wireless communications device104, served by the fourth infrastructure equipment 113.

The second, third and fourth infrastructure equipment 111 to 113 in FIG.4 may each comprise a TRP, broadly similar in functionality to the TRPs10 of FIG. 2.

In some arrangements of the present technique, one or more of the secondto fourth infrastructure equipment 111 to 113 in FIG. 4 may furthercomprise a DU 42, and in some arrangements of the present technique, oneor more of the second to fourth infrastructure equipment 110 to 113 maycomprise a DU and a CU.

In some arrangements of the present technique, the CU 40 associated withthe first infrastructure equipment 110 may perform the function of a CUnot only in respect of the first infrastructure equipment 110, but alsoin respect of one or more of the second, the third and the fourthinfrastructure equipment 111 to 113.

In order to provide the transmission of the uplink data or the downlinkdata between a communications device and the core network, a route isdetermined by any suitable means, with one end of the route being aninfrastructure equipment physically connected to a core network and bywhich uplink and downlink traffic is routed to or from the core network.

In the following, the term ‘node’ is used to refer to an entity whichforms a part of a route for the transmission of the uplink data or thedownlink data.

An infrastructure equipment which is physically connected to the corenetwork and operated in accordance with an example arrangement mayprovide communications resources to other infrastructure equipment andso is referred to as a ‘donor node’. An infrastructure equipment whichacts as an intermediate node (i.e. one which forms a part of the routebut is not acting as a donor node) is referred to as a ‘relay node’. Itshould be noted that although such intermediate node infrastructureequipment act as relay nodes on the backhaul link, they may also provideservice to communications devices. The relay node at the end of theroute which is the infrastructure equipment controlling the cell inwhich the communications device is obtaining service is referred to asan ‘end node’.

In the wireless network illustrated in FIG. 4, each of the first tofourth infrastructure equipment 110 to 113 may therefore function asnodes. For example, a route for the transmission of uplink data from thefourth communications device 104 may consist of the fourthinfrastructure equipment 113 (acting as the end node), the thirdinfrastructure equipment 112 (acting as a relay node), and the firstinfrastructure equipment 110 (acting as the donor node). The firstinfrastructure 110, being connected to the core network 20, transmitsthe uplink data to the core network 20.

For clarity in the following description, the infrastructure equipment110 is referred to below as the ‘donor node’, the first infrastructureequipment 111 is referred to below as ‘Node 1’, the secondinfrastructure equipment 112 is referred to below as ‘Node 2’ and thethird infrastructure equipment 113 is referred to below as ‘Node 3’.

For the purposes of the present disclosure, the term ‘upstream node’ isused to refer to a node acting as a relay node or a donor node in aroute, which is a next hop when used for the transmission of data viathat route from a wireless communications device to a core network.Similarly, ‘downstream node’ is used to refer to a relay node from whichuplink data is received for transmission to a core network. For example,if uplink data is transmitted via a route comprising (in order) the Node3 113, the Node 1 111 and the donor node 110, then the donor node 110 isan upstream node with respect to the Node 1 111, and the Node 3 113 is adownstream node with respect to the Node 1 111.

More than one route may be used for the transmission of the uplink datafrom a given communications device; this is referred to herein as‘multi-connectivity’. For example, the uplink data transmitted by thewireless communications device 104 may be transmitted either via theNode 3 113 and the Node 2 112 to the donor node 110, or via the Node 3113 and the Node 1 111 to the donor node 110.

In the following description, example arrangements are described inwhich each of the nodes is an infrastructure equipment; the presentdisclosure is not so limited. A node may comprise at least atransmitter, a receiver and a controller. In some arrangements of thepresent technique, the functionality of a node (other than the donornode) may be carried out by a communications device, which may be thecommunications device 4 (of FIG. 1) or 14 (of FIG. 2), adaptedaccordingly. As such, in some arrangements of the present technique, aroute may comprise one or more communications devices. In otherarrangements, a route may consist of only a plurality of infrastructureequipment.

In some arrangements of the present technique, an infrastructureequipment acting as a node may not provide a wireless access interfacefor the transmission of data to or by a communications device other thanas part of an intermediate transmission along a route.

In some arrangements of the present technique, a route is definedconsidering a wireless communications device (such as the wirelesscommunications device 104) as the start of a route. In otherarrangements a route is considered to start at an infrastructureequipment which provides a wireless access interface for thetransmission of the uplink data by a wireless communications device.

Integrated Access and Backhaul (IAB) for NR

A new study item on Integrated Access and Backhaul for NR [3] has beenapproved. Several requirements and aspects for the integrated access andwireless backhaul for NR to address are discussed in [3], which include:

-   -   Efficient and flexible operation for both inband and outband        relaying in indoor and outdoor scenarios;    -   Multi-hop and redundant connectivity;    -   End-to-end route selection and optimisation;    -   Support of backhaul links with high spectral efficiency;    -   Support of legacy NR UEs.

The stated objective of the study detailed in [3] is to identify andevaluate potential solutions for topology management forsingle-hop/multi-hop and redundant connectivity, route selection andoptimisation, dynamic resource allocation between the backhaul andaccess links, and achieving high spectral efficiency while alsosupporting reliable transmission.

FIG. 5 shows the scenario presented in [3], where a backhaul link isprovided from cell site A 501 to cells B 502 and C 504 over the air. Itis assumed that cells B 502 and C 504 have no wired backhaulconnectivity. Considering the CU/DU split architecture in NR asdescribed above, it can be assumed that all of cells A 501, B 502 and C504 have a dedicated DU unit and are controlled by the same CU.

Several architecture requirements for IAB are laid out in [4]. Theseinclude the support for multiple backhaul hops, that topology adaptationfor physically fixed relays shall be supported to enable robustoperation, minimisation of impact to core network specifications,consideration of impact to core networking signalling load, and Release15 NR specifications should be reused as much as possible in the designof the backhaul link, with enhancements considered.

FIG. 6 is reproduced from [5], and shows an example of a wirelesscommunications system comprising a plurality of IAB-enabled nodes, whichmay for example be TRPs forming part of an NR network. These comprise anIAB donor node 601 which has a connection to the core network, two IABnodes (a first IAB node 602 and a second IAB node 604) which havebackhaul connections to the IAB donor node 601, and a third IAB node 606(or end IAB node) which has a backhaul connection to each of the firstIAB node 602 and the second IAB node 604. Each of the first IAB node 601and third IAB node 606 have wireless access connections to UEs 608 and610 respectively. As shown in FIG. 6, originally the third IAB node 606may communicate with the IAB donor node 601 via the first IAB node 602.After the second IAB node 604 emerges, there are now two candidateroutes from the third IAB node 606 to the IAB donor node 601; via thefirst IAB node 602 and via the new second IAB node 604. The newcandidate route via the second IAB node 604 will play an important rolewhen there is a blockage in the first IAB node 602 to IAB donor node 604link. Hence, knowing how to manage the candidate routes efficiently andeffectively is important to ensure timely data transmission betweenrelay nodes, especially when considering the characteristics of wirelesslinks.

Given the dynamic characteristics of wireless links, in which new nodesmay emerge, existing nodes may disappear, and/or link quality betweenvarious nodes may deteriorate or improve with time, efficient and robusttechniques for dynamically adding/deleting/updating peer-to-peer linkinformation in order to maintain up-to-date route information must bedeveloped. This is particularly true for systems comprising multiplehops, which further complicate routing.

In order to overcome the above, and considering multi-hops on thebackhaul link and that topology adaptation should be considered in thecase that blockages or congestion occur in the backhaul link,embodiments of the present technique seek to address route management inbackhaul links. This route management includes route addition, routeupdating and route deletion; hence enabling efficient topologymanagement.

Candidate Route Management in IAB

FIG. 7 shows a part schematic, part message flow diagram ofcommunications in a wireless communications network 700 in accordancewith embodiments of the present technique. The wireless communicationsnetwork 700 comprising a plurality of infrastructure equipment 702, 704,706, 708 each being configured to communicate with one or more others ofthe infrastructure equipment 702, 704, 706, 708 via a backhaulcommunications link 712, one or more of the infrastructure equipment702, 704, 706, 708 each being configured to communicate with one or morecommunications devices 720 via a wireless access interface 714, whereina first of the infrastructure equipment 702 is configured to act as adonor node connected to a core network part 701 of the wirelesscommunications network 700 and comprises transceiver circuitry 702 a andcontroller circuitry 702 b configured in combination to receive 730,from a second of the infrastructure equipment 708, information 732, 734relating to each of a plurality of different communications paths fromthe second infrastructure equipment 708 to the first infrastructureequipment 702 via one or more others of the infrastructure equipment704, 706 acting as relay nodes, to determine 740, based on the receivedinformation relating to the plurality of different communications paths730, that either at least a part of a new communications path existsbetween the first of the infrastructure equipment 702 and the second ofthe infrastructure equipment 708 or at least a part of a previouslyknown communications path no longer exists between the first of theinfrastructure equipment 702 and the second of the infrastructureequipment 708, and to update 750 a communications path list by eitheradding the at least the part of the new communications path or deletingthe at least the part of the previously known communications path thatno longer exists.

The at least the part of the new communications path or the at least thepart of the previously known communications path may in some cases bethe whole path from the donor node (the first infrastructure equipment)to the end node (the second infrastructure equipment) via the relaynodes (the one or more others of the infrastructure equipment acting asthe relay nodes). However in other cases, the at least the part of thenew communications path or the at least the part of the previously knowncommunications path may be a single or multiple hops without being thewhole path from the donor node to the end node (e.g. the end node to thenext hop relay node, or between two relay nodes, or between a relay nodeto the donor node).

Here, the information relating to the plurality of differentcommunications paths may be measurement reports on whether the link isgood or bad as shown in FIG. 7, or may alternatively be load informationon whether the node load is high, medium and low, or may relate to theload balancing strategy at the donor node i.e. although the link qualityis good, the route may still not be selected for load balancing reasons.

Route Addition

When a new relay node (it should be appreciated that in embodiments ofthe present technique, this may be an eNodeB/TRP, a UE, or otherinfrastructure equipment) emerges, for example through random access toa previous hop relay node and declares itself as a relay node (orotherwise gets instructions to do so from the core network), thispotentially new route information should be recorded and also should beforwarded to the donor node if necessary. For example, taking the systemof FIG. 6, if the second IAB node 604 has newly emerged and declaresitself as a relay node, the IAB donor node 601 will record a new routefrom the IAB donor node 601 to the second IAB node 604. The third (end)IAB node 606 will send a measurement report to the first IAB node 602with the inclusion of a link quality (if this is above a certainthreshold) between the second IAB node 604 and the third IAB node 606.In other words, the determining that the at least the part of the newcommunications path exists comprises determining from the receivedinformation that a link quality between two of the infrastructureequipment forming part of the at least the part of the newcommunications path is above a predetermined threshold.

Then, the first IAB node 602 will realise that there is a potential newroute from the IAB donor node 601 to the third (end) IAB node 606 viathe second IAB node 604, in addition to the known route via the firstIAB node 602, or at least realise the potential part of this new routefrom the IAB donor node 601 to the second IAB node 604. The first IABnode 602 will record the new route and at the same time it may notifythis information to its previous hop relay node as well, it has one.Then, the IAB donor node 601 may record this new candidate route as IABdonor node 601 to second IAB node 604 to third IAB node 606.

It should be noted that it is up to the IAB donor node's 601implementation to record the entire route as one as above, or separatelyin its constituent parts as IAB donor node 601 to second IAB node 604and second IAB node 604 to third IAB node 606, or in the form of{destination, next-hop} e.g. {third IAB node 606, second IAB node 604}.In other words, the communications path list is updated by the firstinfrastructure equipment and comprises each of the known communicationspaths between the first infrastructure equipment and the secondinfrastructure equipment via the infrastructure equipment acting as therelay nodes, or the communications path list is updated by the firstinfrastructure equipment and comprises each of the known communicationspaths between the first infrastructure equipment and the otherinfrastructure equipment.

Alternatively, different nodes could record part of the routeindependently; i.e. IAB donor node 601 may record the part of the IABdonor node 601 to second IAB node 604, while the second IAB node 604 mayrecord the part of the second IAB node 604 to third IAB node 606. Thedonor node 601 here distributes routing information to the second IABnode 604 (or indeed to any node which records any part of a route) suchthat the second IAB node 604 is able to record the part of the routefrom the second IAB node 604 to third IAB node 606. In other words, thecommunications path list is updated by a plurality of the infrastructureequipment, each of the plurality of the infrastructure equipmentupdating at least part of the communications path list.

In an arrangement, the first IAB node 602 could forward the measurementreport from the third IAB node 606, including the measurement results ofthe path between the third IAB node 606 and the second IAB node 604, tothe IAB donor node 601, then the IAB donor node 601 would be able todeduce that there could be a potential route comprising the path betweenthe third IAB node 606 and the second IAB node 604. In other words, theinformation is received at the first infrastructure equipment from thesecond infrastructure equipment via a known communications pathcomprising one or more others of the infrastructure equipment acting asrelay nodes.

This routing information may be sent, for example, via a dedicated RRCsignaling, or using a MAC control element (CE), or via F1 interfaceapplication protocol (AP) signalling.

However, before the new route is actually activated, admission controlshould be conducted in advance at the second IAB node 604. There areseveral options through which to do this.

-   -   The donor node 601 asks for the admission on behalf of the end        node 606. For example, after the IAB donor node 601 gets the        candidate route information of the second IAB node 604 to the        third IAB node 606, it will send the admission request to the        second IAB node 604 on behalf of the third IAB node 606. If the        second IAB node 604 accepts the admission, it may send, for        example, a reserved preamble for random access or reserved        resources for data transmission to the IAB donor node 601. The        IAB donor node 601 may then forward these allocations to the        third IAB node 606. The admission request could be sent using        any one of: RRC dedicated signalling, physical layer signaling,        MAC CE or F1-AP message, DU-DU signalling or X2-AP message. In        other words, conducting the admission control using this option        comprises transmitting an admission request for the at least the        part of the new communications path, by the first infrastructure        equipment, to an intermediate infrastructure equipment forming        part of the at least the part of the new communications path        between the first infrastructure equipment and the second        infrastructure equipment, receiving, at the first infrastructure        equipment an admission request acceptance signal from the        intermediate infrastructure equipment, and communicating, by the        first infrastructure equipment, with the second infrastructure        equipment via the new communications path comprising the        intermediate infrastructure equipment.    -   The end node 606 asks for the admission by itself. For example,        the third IAB node 606 finds the existence of the second IAB        node 604 via making measurements, and will initiate a random        access procedure. The second IAB node 604 will then decide        whether it will accept the access request or not. If the third        IAB node 606 successfully accesses the second IAB node 604, it        will send the route information, of the second IAB node 604 to        the third IAB node 606, to the IAB donor node 601. The admission        request may be inferred from a reserved preamble resource or a        message transmitted after a random access procedure e.g. MSG3 or        MSG3.5 or MSG 5. In other words, conducting the admission        control using this option comprises transmitting an admission        request for the at least the part of the new communications        path, by the second infrastructure equipment, to an intermediate        infrastructure equipment forming part of the at least the part        of the new communications path between the first infrastructure        equipment and the second infrastructure equipment, receiving, at        the second infrastructure equipment an admission request        acceptance signal from the intermediate infrastructure        equipment, transmitting, by the second infrastructure equipment,        an indication of the admission request acceptance signal to the        first infrastructure equipment, and communicating, by the first        infrastructure equipment, with the second infrastructure        equipment via the new communications path comprising the        intermediate infrastructure equipment.    -   The intermediate node 604 may declare it is part of a new        route/path by itself. The intermediate node 604 will broadcast        its access barring information via system information. The end        node 606 should read its system information before sending the        candidate route information. The end node 606 is in RRC        Connected mode already but may treat itself as being in IDLE        mode while accessing a new node, for the purpose of redundancy        or load balancing. In other words, conducting the admission        control using this option comprises broadcasting, by an        intermediate infrastructure equipment forming part of the at        least the part of the new communications path between the first        infrastructure equipment and the second infrastructure        equipment, an admission acceptance signal of the at least the        part of the new communications path, and communicating, by the        first infrastructure equipment, with the second infrastructure        equipment via the new communications path comprising the        intermediate infrastructure equipment.        Route Deletion

Similarly to the situation of route addition, when an existing route isno longer feasible, the corresponding route information should beupdated accordingly.

For example, route deletion may be required if an IAB node disappearssuddenly or the link quality between the second IAB node 604 and thethird IAB node 606 is not good anymore (e.g. it falls below apredetermined threshold). In other words, the determining that the atleast the part of the previously known communications path no longerexists comprises determining from the received information that a linkquality between two of the infrastructure equipment forming part of theat least the part of the previously known communications path is below apredetermined threshold.

The first IAB node 602 may detect such an occurrence, for example, fromthe measurement report of the third IAB node 606, or the IAB donor node601 may detect it, for example, by sending data to the second IAB node604 without receiving any acknowledgement. In the first case, the firstIAB node 602 may delete the route information of the second IAB node 604to the third IAB node 606 and may inform the IAB donor node 601 of thisas well. In the second case, the IAB donor node 601 may delete the routeinformation of the path between itself and the second IAB node 604 (aswell as that between the second IAB node 604 and the third IAB node606).

Alternatively, the determining that the at least the part of thepreviously known communications path no longer exists comprisesdetermining from the received information that the one of theinfrastructure equipment acting as the relay nodes through which thecommunications path passes is no longer visible to the otherinfrastructure equipment on the at least the part of the previouslyknown communications path. For example, one of the nodes on the routemay have moved out of range of the other nodes on the route (or at leastout of range of one of the next hop nodes on the route), or may have hada power issue or failure of some kind and has as such “disappeared” fromthe point of view of the other nodes on the path.

As another alternative, the determining that the at least the part ofthe previously known communications path no longer exists comprisesdetermining from the received information that one of the infrastructureequipment has indicated that the at least the part of the previouslyknown communications path should no longer exist. The indication thatthe previously known communications path should know longer exist may betransmitted by one of the nodes on the (previously known) communicationspath in response to a particular or predetermined trigger, and receivedby the donor node as at least part of the information relating to thecommunications paths. Here, the IAB node can initiate route deletion ormodification any time towards another node (either upstream ordownstream). The trigger may be based on an overload at a node or due toload balancing requirements. This situation may occur after the routehas been accepted initially, but later on due to, for example, trafficfrom normal UEs having increased or due to, for example, a change inradio conditions, the other node may either share the load or take overcompletely, thus requiring deletion or modification of the previouslyknown communications path in the route table (communications path list).

Again, as above, this route information may be sent, for example, via adedicated RRC signaling or MAC CE or F1-AP or X2-AP or similar.

Flow Chart Representation

FIG. 8 shows a flow diagram illustrating a process of communications ina communications system in accordance with embodiments of the presenttechnique. The process shown by FIG. 8 is a method of controllingcommunications within a wireless communications network comprising aplurality of infrastructure equipment each being configured tocommunicate with one or more others of the infrastructure equipment viaa backhaul communications link, one or more of the infrastructureequipment each being configured to communicate with one or morecommunications devices via a wireless access interface.

The method begins in step S801. The method comprises, in step S802,receiving, at a first of the infrastructure equipment acting as a donornode connected to a core network part of the wireless communicationsnetwork, from a second of the infrastructure equipment, informationrelating to each of a plurality of different communications paths fromthe second infrastructure equipment to the first infrastructureequipment via one or more others of the infrastructure equipment actingas relay nodes. The process proceeds to step S804, which comprisesdetermining, based on the received information relating to the pluralityof different communications paths, that at least a part of a newcommunications path exists between the first of the infrastructureequipment and the second of the infrastructure equipment. If the outcomeof this determination is positive, i.e. a new route does exist, then themethod proceeds to step S808, which comprises updating a communicationspath list by adding the at least the part of the new communicationspath. If however, the outcome of the determination is negative, i.e. nonew route exists, then the process proceeds to step S806, whichcomprises determining, based on the received information relating to theplurality of different communications paths, that at least a part of apreviously known communications path no longer exists between the firstof the infrastructure equipment and the second of the infrastructureequipment. If the outcome of this determination is positive, i.e. apreviously known route no longer exists, then the method again proceedsto step S808, which comprises updating the communications path list bydeleting the at least the part of the previously known communicationspath that no longer exists. If however, the outcome of thisdetermination is negative, i.e. no previously known routes aredetermined to no longer exist, then the infrastructure equipment willcontinue to receive information relating to the plurality of differentcommunications paths and monitor for the potential addition or deletionof routes. The process ends in step S810.

Those skilled in the art would appreciate that the method shown by FIG.8 may be adapted in accordance with embodiments of the presenttechnique. For example, other intermediate steps may be included in themethod, or the steps may be performed in any logical order, such as thedetermination as to whether or not an existing path no longer existsbeing made before the determination as to whether or not a new pathexists is made.

Though embodiments of the present technique have been described by wayof the example systems shown in FIGS. 6 and 7, it would be clear tothose skilled in the art that they could be equally applied to othersystems, where for example there may be many more nodes or paths tochoose from, or more hops between the donor and end nodes.

Those skilled in the art would also appreciate that such infrastructureequipment and/or wireless communications networks as herein defined maybe further defined in accordance with the various arrangements andembodiments discussed in the preceding paragraphs. It would be furtherappreciated by those skilled in the art that such infrastructureequipment and wireless communications networks as herein defined anddescribed may form part of communications systems other than thosedefined by the present invention.

The following numbered paragraphs provide further example aspects andfeatures of the present technique:

Paragraph 1. A method of controlling communications within a wirelesscommunications network comprising a plurality of infrastructureequipment each being configured to communicate with one or more othersof the infrastructure equipment via a backhaul communications link, oneor more of the infrastructure equipment each being configured tocommunicate with one or more communications devices via a wirelessaccess interface, the method comprising

-   -   receiving, at a first of the infrastructure equipment acting as        a donor node connected to a core network part of the wireless        communications network, from a second of the infrastructure        equipment, information relating to each of a plurality of        different communications paths from the second infrastructure        equipment to the first infrastructure equipment via one or more        others of the infrastructure equipment acting as relay nodes,    -   determining, based on the received information relating to the        plurality of different communications paths, that either at        least a part of a new communications path exists between the        first of the infrastructure equipment and the second of the        infrastructure equipment or at least a part of a previously        known communications path no longer exists between the first of        the infrastructure equipment and the second of the        infrastructure equipment, and    -   updating a communications path list by either adding the at        least the part of the new communications path or deleting the at        least the part of the previously known communications path that        no longer exists.

Paragraph 2. A method according to Paragraph 1, wherein the determiningthat the new communications path exists comprises determining from thereceived information that a link quality between two of theinfrastructure equipment forming part of the at least the part of thenew communications path is above a predetermined threshold.

Paragraph 3. A method according to Paragraph 1 or Paragraph 2, whereinthe determining that the at least the part of the previously knowncommunications path no longer exists comprises determining from thereceived information that a link quality between two of theinfrastructure equipment forming part of the previously knowncommunications path is below a predetermined threshold.

Paragraph 4. A method according to any of Paragraphs 1 to 3, wherein thedetermining that the at least the part of the previously knowncommunications path no longer exists comprises determining from thereceived information that the one of the infrastructure equipment actingas the relay nodes through which the communications path passes is nolonger visible to the other infrastructure equipment on the previouslyknown communications path.

Paragraph 5. A method according to any of Paragraphs 1 to 4, wherein thedetermining that the at least the part of the previously knowncommunications path no longer exists comprises determining from thereceived information that one of the infrastructure equipment hasindicated that the previously known communications path should no longerexist.

Paragraph 6. A method according to any of Paragraphs 1 to 5, wherein thecommunications path list is updated by the first infrastructureequipment and comprises each of the known communications paths betweenthe first infrastructure equipment and the second infrastructureequipment via the infrastructure equipment acting as the relay nodes.

Paragraph 7. A method according to any of Paragraphs 1 to 6, wherein thecommunications path list is updated by the first infrastructureequipment and comprises each of the known communications paths betweenthe first infrastructure equipment and the other infrastructureequipment.

Paragraph 8. A method according to any of Paragraphs 1 to 7, wherein thecommunications path list is updated by a plurality of the infrastructureequipment, each of the plurality of the infrastructure equipmentupdating at least part of the communications path list.

Paragraph 9. A method according to any of Paragraphs 1 to 8, wherein theinformation relating to the plurality of different communications pathsis received at the first infrastructure equipment from the secondinfrastructure equipment via a known communications path comprising oneor more others of the infrastructure equipment acting as relay nodes.

Paragraph 10. A method according to any of Paragraphs 1 to 9, comprising

-   -   transmitting an admission request for the at least the part of        the new communications path, by the first infrastructure        equipment, to an intermediate infrastructure equipment forming        part of the at least the part of the new communications path        between the first infrastructure equipment and the second        infrastructure equipment,    -   receiving, at the first infrastructure equipment an admission        request acceptance signal from the intermediate infrastructure        equipment, and    -   communicating, by the first infrastructure equipment, with the        second infrastructure equipment via the new communications path        comprising the intermediate infrastructure equipment.

Paragraph 11. A method according to any of Paragraphs 1 to 10,comprising

-   -   transmitting an admission request for the at least the part of        the new communications path, by the second infrastructure        equipment, to an intermediate infrastructure equipment forming        part of the at least the part of the new communications path        between the first infrastructure equipment and the second        infrastructure equipment, receiving, at the second        infrastructure equipment an admission request acceptance signal        from the intermediate infrastructure equipment, transmitting, by        the second infrastructure equipment, an indication of the        admission request acceptance signal to the first infrastructure        equipment, and communicating, by the first infrastructure        equipment, with the second infrastructure equipment via the new        communications path comprising the intermediate infrastructure        equipment.

Paragraph 12. A method according to any of Paragraphs 1 to 11,comprising

-   -   broadcasting, by an intermediate infrastructure equipment        forming part of the at least the part of the new communications        path between the first infrastructure equipment and the second        infrastructure equipment, an admission acceptance signal of the        at least the part of the new communications path, and    -   communicating, by the first infrastructure equipment, with the        second infrastructure equipment via the new communications path        comprising the intermediate infrastructure equipment.

Paragraph 13. A wireless communications network comprising a pluralityof infrastructure equipment each being configured to communicate withone or more others of the infrastructure equipment via a backhaulcommunications link, one or more of the infrastructure equipment eachbeing configured to communicate with one or more communications devicesvia a wireless access interface, wherein a first of the infrastructureequipment is configured to act as a donor node connected to a corenetwork part of the wireless communications network and comprisestransceiver circuitry and controller circuitry configured in combination

-   -   to receive, from a second of the infrastructure equipment,        information relating to each of a plurality of different        communications paths from the second infrastructure equipment to        the first infrastructure equipment via one or more others of the        infrastructure equipment acting as relay nodes,    -   to determine, based on the received information relating to the        plurality of different communications paths, that either at        least a part of a new communications path exists between the        first of the infrastructure equipment and the second of the        infrastructure equipment or at least a part of a previously        known communications path no longer exists between the first of        the infrastructure equipment and the second of the        infrastructure equipment, and    -   to update a communications path list by either adding the at        least the part of the new communications path or deleting the at        least the part of the previously known communications path that        no longer exists.

Paragraph 14. Circuitry for a wireless communications network comprisinga plurality of infrastructure equipment each being configured tocommunicate with one or more others of the infrastructure equipment viaa backhaul communications link, one or more of the infrastructureequipment each being configured to communicate with one or morecommunications devices via a wireless access interface, wherein a firstof the infrastructure equipment is configured to act as a donor nodeconnected to a core network part of the wireless communications networkand comprises transceiver circuitry and controller circuitry configuredin combination

-   -   to receive, from a second of the infrastructure equipment,        information relating to each of a plurality of different        communications paths from the second infrastructure equipment to        the first infrastructure equipment via one or more others of the        infrastructure equipment acting as relay nodes,    -   to determine, based on the received information relating to the        plurality of different communications paths, that either at        least a part of a new communications path exists between the        first of the infrastructure equipment and the second of the        infrastructure equipment or at least a part of a previously        known communications path no longer exists between the first of        the infrastructure equipment and the second of the        infrastructure equipment, and    -   to update a communications path list by either adding the at        least the part of the new communications path or deleting the at        least the part of the previously known communications path that        no longer exists.

Paragraph 15. A method of operating a first infrastructure equipmentforming part of a wireless communications network comprising a pluralityof other infrastructure equipment, the first infrastructure equipmentand the plurality of other infrastructure equipment each beingconfigured to communicate with one or more others of the infrastructureequipment via a backhaul communications link, one or more of theinfrastructure equipment each being configured to communicate with oneor more communications devices via a wireless access interface, whereinthe first infrastructure equipment is configured to act as a donor nodeconnected to a core network part of the wireless communications network,the method comprising

-   -   receiving, from a second of the infrastructure equipment,        information relating to each of a plurality of different        communications paths from the second infrastructure equipment to        the first infrastructure equipment via one or more others of the        infrastructure equipment acting as relay nodes,    -   determining, based on the received information relating to the        plurality of different communications paths, that either at        least a part of a new communications path exists between the        first of the infrastructure equipment and the second of the        infrastructure equipment or at least a part of a previously        known communications path no longer exists between the first of        the infrastructure equipment and the second of the        infrastructure equipment, and    -   updating a communications path list by either adding the at        least the part of the new communications path or deleting the at        least the part of the previously known communications path that        no longer exists.

Paragraph 16. A first infrastructure equipment forming part of awireless communications network comprising a plurality of otherinfrastructure equipment, the first infrastructure equipment and theplurality of other infrastructure equipment each being configured tocommunicate with one or more others of the infrastructure equipment viaa backhaul communications link, one or more of the infrastructureequipment each being configured to communicate with one or morecommunications devices via a wireless access interface, wherein thefirst infrastructure equipment is configured to act as a donor nodeconnected to a core network part of the wireless communications networkand comprises transceiver circuitry and controller circuitry configuredin combination

-   -   to receive, from a second of the infrastructure equipment,        information relating to each of a plurality of different        communications paths from the second infrastructure equipment to        the first infrastructure equipment via one or more others of the        infrastructure equipment acting as relay nodes,    -   to determine, based on the received information relating to the        plurality of different communications paths, that either at        least a part of a new communications path exists between the        first of the infrastructure equipment and the second of the        infrastructure equipment or at least a part of a previously        known communications path no longer exists between the first of        the infrastructure equipment and the second of the        infrastructure equipment, and    -   to update a communications path list by either adding the at        least the part of the new communications path or deleting the at        least the part of the previously known communications path that        no longer exists.

Paragraph 17. Circuitry for a first infrastructure equipment formingpart of a wireless communications network comprising a plurality ofother infrastructure equipment, the first infrastructure equipment andthe plurality of other infrastructure equipment each being configured tocommunicate with one or more others of the infrastructure equipment viaa backhaul communications link, one or more of the infrastructureequipment each being configured to communicate with one or morecommunications devices via a wireless access interface, wherein thefirst infrastructure equipment is configured to act as a donor nodeconnected to a core network part of the wireless communications networkand comprises transceiver circuitry and controller circuitry configuredin combination

-   -   to receive, from a second of the infrastructure equipment,        information relating to each of a plurality of different        communications paths from the second infrastructure equipment to        the first infrastructure equipment via one or more others of the        infrastructure equipment acting as relay nodes,    -   to determine, based on the received information relating to the        plurality of different communications paths, that either at        least a part of a new communications path exists between the        first of the infrastructure equipment and the second of the        infrastructure equipment or at least a part of a previously        known communications path no longer exists between the first of        the infrastructure equipment and the second of the        infrastructure equipment, and    -   to update a communications path list by either adding the at        least the part of the new communications path or deleting the at        least the part of the previously known communications path that        no longer exists.

It will be appreciated that the above description for clarity hasdescribed embodiments with reference to different functional units,circuitry and/or processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits, circuitry and/or processors may be used without detracting fromthe embodiments.

Described embodiments may be implemented in any suitable form includinghardware, software, firmware or any combination of these. Describedembodiments may optionally be implemented at least partly as computersoftware running on one or more data processors and/or digital signalprocessors. The elements and components of any embodiment may bephysically, functionally and logically implemented in any suitable way.Indeed the functionality may be implemented in a single unit, in aplurality of units or as part of other functional units. As such, thedisclosed embodiments may be implemented in a single unit or may bephysically and functionally distributed between different units,circuitry and/or processors.

Although the present disclosure has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. Additionally, although a feature may appear to bedescribed in connection with particular embodiments, one skilled in theart would recognise that various features of the described embodimentsmay be combined in any manner suitable to implement the technique.

REFERENCES

-   [1] Holma H. and Toskala A, “LTE for UMTS OFDMA and SC-FDMA based    radio access”, John Wiley and Sons, 2009.-   [2] RP-161901, “Revised work item proposal: Enhancements of NB-IoT”,    Huawei, HiSilicon, 3GPP TSG RAN Meeting #73, New Orleans, USA, Sep.    19-22, 2016.-   [3] RP-170831, “New SID Proposal: Study on Integrated Access and    Backhaul for NR”, AT&T, 3GPP RAN Meeting #75, Dubrovnik, Croatia,    March 2017.-   [4] 3GPP TTR 38.874 “3^(rd) Generation Partnership Project;    Technical Specification Group Radio Access Network; Study on    Integrated Access and Backhaul; (Release 15)”, 3^(rd) Generation    Partnership Project, February 2018.-   [5] R2-1801606, “Proposals on IAB Architecture”, Qualcomm et al,    3GPP TSG-RAN WG2 NR Ad hoc 1801, Vancouver, Canada, Jan. 22-26,    2018.

What is claimed is:
 1. A method of controlling communications within awireless communications network comprising a plurality of infrastructureequipment each being configured to communicate with one or more othersof the infrastructure equipment via a backhaul communications link, oneor more of the infrastructure equipment each being configured tocommunicate with one or more communications devices via a wirelessaccess interface, the method comprising receiving, at a first of theinfrastructure equipment acting as a donor node connected to a corenetwork part of the wireless communications network, from a second ofthe infrastructure equipment, information relating to each of aplurality of different communications paths from the secondinfrastructure equipment to the first infrastructure equipment via oneor more others of the infrastructure equipment acting as relay nodes,determining, based on the received information relating to the pluralityof different communications paths, that either at least a part of a newcommunications path exists between the first of the infrastructureequipment and the second of the infrastructure equipment or at least apart of a previously known communications path no longer exists betweenthe first of the infrastructure equipment and the second of theinfrastructure equipment, and updating a communications path list byeither adding the at least the part of the new communications path ordeleting the at least the part of the previously known communicationspath that no longer exists.
 2. A method according to claim 1, whereinthe determining that the new communications path exists comprisesdetermining from the received information that a link quality betweentwo of the infrastructure equipment forming part of the at least thepart of the new communications path is above a predetermined threshold.3. A method according to claim 1, wherein the determining that the atleast the part of the previously known communications path no longerexists comprises determining from the received information that a linkquality between two of the infrastructure equipment forming part of thepreviously known communications path is below a predetermined threshold.4. A method according to claim 1, wherein the determining that the atleast the part of the previously known communications path no longerexists comprises determining from the received information that the oneof the infrastructure equipment acting as the relay nodes through whichthe communications path passes is no longer visible to the otherinfrastructure equipment on the previously known communications path. 5.A method according to claim 1, wherein the determining that the at leastthe part of the previously known communications path no longer existscomprises determining from the received information that one of theinfrastructure equipment has indicated that the previously knowncommunications path should no longer exist.
 6. A method according toclaim 1, wherein the communications path list is updated by the firstinfrastructure equipment and comprises each of the known communicationspaths between the first infrastructure equipment and the secondinfrastructure equipment via the infrastructure equipment acting as therelay nodes.
 7. A method according to claim 1, wherein thecommunications path list is updated by the first infrastructureequipment and comprises each of the known communications paths betweenthe first infrastructure equipment and the other infrastructureequipment.
 8. A method according to claim 1, wherein the communicationspath list is updated by a plurality of the infrastructure equipment,each of the plurality of the infrastructure equipment updating at leastpart of the communications path list.
 9. A method according to claim 1,wherein the information relating to the plurality of differentcommunications paths is received at the first infrastructure equipmentfrom the second infrastructure equipment via a known communications pathcomprising one or more others of the infrastructure equipment acting asrelay nodes.
 10. A method according to claim 1, comprising transmittingan admission request for the at least the part of the new communicationspath, by the first infrastructure equipment, to an intermediateinfrastructure equipment forming part of the at least the part of thenew communications path between the first infrastructure equipment andthe second infrastructure equipment, receiving, at the firstinfrastructure equipment an admission request acceptance signal from theintermediate infrastructure equipment, and communicating, by the firstinfrastructure equipment, with the second infrastructure equipment viathe new communications path comprising the intermediate infrastructureequipment.
 11. A method according to claim 1, comprising transmitting anadmission request for the at least the part of the new communicationspath, by the second infrastructure equipment, to an intermediateinfrastructure equipment forming part of the at least the part of thenew communications path between the first infrastructure equipment andthe second infrastructure equipment, receiving, at the secondinfrastructure equipment an admission request acceptance signal from theintermediate infrastructure equipment, transmitting, by the secondinfrastructure equipment, an indication of the admission requestacceptance signal to the first infrastructure equipment, andcommunicating, by the first infrastructure equipment, with the secondinfrastructure equipment via the new communications path comprising theintermediate infrastructure equipment.
 12. A method according to claim1, comprising broadcasting, by an intermediate infrastructure equipmentforming part of the at least the part of the new communications pathbetween the first infrastructure equipment and the second infrastructureequipment, an admission acceptance signal of the at least the part ofthe new communications path, and communicating, by the firstinfrastructure equipment, with the second infrastructure equipment viathe new communications path comprising the intermediate infrastructureequipment.
 13. A method of operating a first infrastructure equipmentforming part of a wireless communications network comprising a pluralityof other infrastructure equipment, the first infrastructure equipmentand the plurality of other infrastructure equipment each beingconfigured to communicate with one or more others of the infrastructureequipment via a backhaul communications link, one or more of theinfrastructure equipment each being configured to communicate with oneor more communications devices via a wireless access interface, whereinthe first infrastructure equipment is configured to act as a donor nodeconnected to a core network part of the wireless communications network,the method comprising receiving, from a second of the infrastructureequipment, information relating to each of a plurality of differentcommunications paths from the second infrastructure equipment to thefirst infrastructure equipment via one or more others of theinfrastructure equipment acting as relay nodes, determining, based onthe received information relating to the plurality of differentcommunications paths, that either at least a part of a newcommunications path exists between the first of the infrastructureequipment and the second of the infrastructure equipment or at least apart of a previously known communications path no longer exists betweenthe first of the infrastructure equipment and the second of theinfrastructure equipment, and updating a communications path list byeither adding the at least the part of the new communications path ordeleting the at least the part of the previously known communicationspath that no longer exists.
 14. Circuitry for a first infrastructureequipment forming part of a wireless communications network comprising aplurality of other infrastructure equipment, the first infrastructureequipment and the plurality of other infrastructure equipment each beingconfigured to communicate with one or more others of the infrastructureequipment via a backhaul communications link, one or more of theinfrastructure equipment each being configured to communicate with oneor more communications devices via a wireless access interface, whereinthe first infrastructure equipment is configured to act as a donor nodeconnected to a core network part of the wireless communications networkand comprises transceiver circuitry and controller circuitry configuredin combination to receive, from a second of the infrastructureequipment, information relating to each of a plurality of differentcommunications paths from the second infrastructure equipment to thefirst infrastructure equipment via one or more others of theinfrastructure equipment acting as relay nodes, to determine, based onthe received information relating to the plurality of differentcommunications paths, that either at least a part of a newcommunications path exists between the first of the infrastructureequipment and the second of the infrastructure equipment or at least apart of a previously known communications path no longer exists betweenthe first of the infrastructure equipment and the second of theinfrastructure equipment, and to update a communications path list byeither adding the at least the part of the new communications path ordeleting the at least the part of the previously known communicationspath that no longer exists.